CAR-T Cell Therapy

Question 1

What does CAR-T mean?

Answer 1

Chimeric Antigen Receptor T-cell

Question 2

What is the aim of CAR-T therapy?

Answer 2

[Different cancer cells have different antigens on their surface, and some can only be found on foreign tumour cells.]
If we engineer a T-cell that will attach itself to a very specific antigen that’s ONLY found on cancer cells, then we can reprogram the immune system to recognise the cancer cells.

Question 3

What exactly does CAR-T cell therapy do?

Answer 3

It takes the natural binding of antigens to T-cell receptors by engineering the patient’s T-cells to express a different version of a T-cell receptor, we can redirect the patient’s own T-cells against the cancer antigens expressed on their cancer cells. This can selectively target oncoproteins.

Question 4

How does a T-cell receptor work?

Answer 4

T-cell receptors are protein complexes found on the surface of T-cells which recognise fragments of antigens bound to MHC molecules.

Question 5

How exactly do T-cell receptors recognise their antigens and what happens to activate the T-cells?

Answer 5

3 signals are needed to activate T-cells:

1. Binding of antigen to TCR which activates CD3-ζ domain → causes activation of signals through phosphorylation of proteins nearby.
2. Co-stimulatory signal → proteins like CD28 or 4-1BB are needed to add a primary signal to enhance TCR activation.
3. Cytokine-mediated differentiation and expansion of activated T-cells.

Question 6

How are CAR-T cells made?

Answer 6

Gene is inserted into the T cell using a viral vector (can be an inactivated virus that carries a specific gene) and it is released into the cell where the T-cell will engulf it and encode and reprogram the specific message.
The gene then carries the instructions to express a specific receptor on the T-cell’s outer surface.

Question 7

What are the THREE domains of a CAR and their roles?

Answer 7

1. Antigen binding domain - recognises the tumour/target cell
2. Transmembrane domain - supports the stability of the CAR
3. Intracellular domain - facilitates signal transduction + activates T-cells after antigen recognition

Question 8

What is the key difference between 1st & 2nd generation CARs?

Answer 8

1st gen: only have ABD + TMDs
There is no co-stimulation to give it a second signal for full activation.
∴ It’s more susceptible to apoptosis + limited in vivo expansion in cytotoxicity

2nd gen: CONTAINS CO-STIMULATORY DOMAIN = promotes IL-2 secretion → promotes T-cell activation and prevents apoptosis.

Question 9

What are the 2 most common co-stimulatory domains?

Answer 9

CD28 and 4-1BB

Question 10

How do patients receive CAR-T cell therapy treatment?

Answer 10

1. Local hospital or referral centres identify eligible patients for treatment
2. Patient case will be discussed by the national CAR-T panel to establish eligibility.
3. After approval, the patient will undergo LEUKAPHERESIS (= collection of T cells) and this is sent to a manufacturer who will make their CAR-T cells.
4. Patient may have bridging therapy in the mean time to stop their disease rapidly progressing.
5. When T-cells are made, the patient is taken to a CAR-T cell centre for LYMPHODEPLETION to make space in the patient’s bone marrow so they can receive CAR-T cells.
6. Patient will have CAR-T cells infused into them 2 days after lymphodepletion is complete.
7. Once the CAR-T cells have been infused into the patient, they are monitored for at least 10 days for acute toxicities.
8. Patient may be discharged between day 10-28, depending on their tolerance.
9. Patient will need long-term monitoring at their hospital and management of late onset of their disease.

Question 11

What is leukapheresis?

Answer 11

Collection of the patient’s T-cells.

A machine is used to separate the blood components and remove the patient’s lymphocytes . The blood is infused back into the patient.

Question 12

What must we check before carrying out leukapheresis?

Answer 12

i. What treatment the patient has already had, and if enough time has passed for drugs to be fully eliminated from the body.

ii. If any drugs taken recently had an effect on the patient’s T-cells which may affect the starting material.

iii. Confirm washout period - ensure any drugs taken (up to 3 months before Tx) that can affect T-cells are washed out.

Question 13

Why are all T-cells analogous products?

Answer 13

Each product is different as it uses the patient’s T-cells, so they will not be the same (this is different to other conventional medicines which follow a strict specification)

Question 14

What does it mean if a T-cell product is ‘Out of Specification’?

Answer 14

1 or more criteria are not met. However, this does NOT mean it’s unlicensed. The doctor can still confirm its use if they deem it appropriate for the patient.

Question 15

What are the aims of bridging therapy?

Answer 15

Control active disease + avoid progression
Minimal toxicities
Avoid patient harm
Prevent delay in CAR-T cell infusion

Question 16

Why do we not want to eradicate the disease by using bridging therapy?

Answer 16

We need the disease to be present so CAR-T cells can attach and kill the cancer cells

Question 17

What are the aims of lymphodepletion?

Answer 17

Create space in the bone marrow for a more favourable immune environment for CAR-T cells to expand and persist.

Question 18

What verification checks are done by the pharmacists for lymphodepletion?

Answer 18

1. Lymphodepletion that’s received is safe + appropriate for the patient
2. Check that blood results + organ function tests are safe to allow Tx
3. Disease burden is low enough to safely administer CAR-Ts
4. Check dose calculated for the patient is correct for their height, weight and organ function
5. Appropriate Tx schedule written on Rx
6. CAR-Ts are successfully manufactured
7. Check washout periods for bridging therapy
8. Check if supportive care management has been prescribed

Question 19

What supportive medicines may be given to the patient and why?

Answer 19

Anti-emetics - given to minimise emesis (side effect of lymphodepletion)

PPI or H2 antagonist - to ↓ stomach acid build up and to prevent mucositis

Allopurinol - to prevent tumour lysis syndrome that can occur when CAR-Ts start killing cancer cells

Anti-epileptics - to prevent seizures (side effects of CAR-T therapy)

Antivirals, antibiotics and antifungals

Question 20

What checks need to be done on the day that the CAR-T cells are to be infused?

Answer 20

1. Patient has completed ALL days of lymphodepletion and there has been a correct interval between the last day of Tx and CAR-T infusion
2. Patient is fut to receive CAR-T and has NO SIGNS of infection
3. CAR-T has been stored properly
4. Check cells have not been thawed during storage + transportation
5. Check the patient’s details in the final product and match the patients’s details to the Rx
6. Visual check of product

Question 21

How are CAR-T cells prepared for infusion?

Answer 21

Frozen final product is thawed in a water bath at 37C